ABSTRACT Introduction: Hemolytic uremic syndrome (HUS) is defined as a triad of microangiopathic hemolytic anemia (MHA), thrombocytopenia, and acute renal failure. It is the most common cause of acute renal failure in children, and the incidence of this syndrome is increasing worldwide. Angiopoietin-1 and -2 each competitively bind to the endothelial Tie-2 receptor and play an important role in regulating endothelial cell function. The aim of this study was investigating the clinical significance of serum levels of angiopoietin (Ang) 1 and 2 in enterohemorrhagic Escherichia Coli (EHEC) induced HUS and determining their correlation with disease severity. Patients and Methods: Forty eight children aged between 1-16 years were included in the study and were divided into two groups, 24 patients with diagnosis of hemolytic uremic syndrome induced by EHEC infection and 24 healthy children as a control group. Serum samples were obtained from healthy control group and patients with EHEC-induced HUS at time of diagnosis. Serum samples from the patients were obtained for analysis for angiopoietin-1 and -2 by enzyme-linked immunosorbent assay. Results: Our findings indicated that, serum Ang-1 levels might be useful for the prediction of the development of HUS. In HUS phase, in addition to more significant decrease of serum Ang-1 levels, serum Ang-2 level increased. These changes might be useful for the diagnosis of HUS and also be useful as a marker of disease activity of HUS. Conclusion: Serum angiopoietin-1 and angiopoietin-2 levels and the Ang-2/Ang-1 ratio may be promising indicators of disease activity in HUS.